Control and automatic regulation device for cathodic protection systems in reinforced concrete structures

Abstract

Device for the control and regulation of the feeding unit (60), as well as for monitoring of impressed current cathodic protection systems in reinforced concrete in order to avoid any risks of reinforcement (10) over-protection and to prevent hydrogen embrittlement problems, while assuring full protection of reinforcements.

We claim: 
     
       1. A cathodic protection system comprising: a metallic reinforcement member embedded in concrete;   an anode structure overlaying the concrete in which the metallic reinforcement member is embedded;   a reference electrode embedded in the concrete between the metallic reinforcement member and the anodic structure;   power supply means connected to the anode structure by anodic feeding cables and to the metallic reinforcement member for supplying a voltage, whereby the metallic reinforcement member behaves as a cathode;   control means connected to the power supply unit to receive a signal having a value E, the control means also being connected to the reference electrode to receive a signal having a value Ea,on, the control means further being connected to the power supply unit for adjusting the voltage supplied thereby whereby   -E+Ea,on+E        is greater than a predetermined minimum protection potential, and wherein E is a value indicative of the voltage of the power supply unit; Ea,on is a value indicative of a potential between the anode structure and the reference electrode; and, Em is a value indicative of ohmic drops in the anodic structure and the anodic feeding cables.   
     
     
       2. The apparatus of claim 1, wherein the power supply unit operates at a constant voltage. 
     
     
       3. The apparatus of claim 1, wherein the power supply unit operates at a constant current. 
     
     
       4. The apparatus of claim 1, wherein the predetermined minimum protection potential is -0.90 volts with respect to a Ag/AgCl electrode for pre-stressed concrete. 
     
     
       5. The apparatus of claim 1, wherein the predetermined minimum protection potential is -1.1 volts with respect to a Ag/AgCl electrode for reinforced concrete. 
     
     
       6. The apparatus of claim 1, further having a plurality of reference electrodes embedded in the concrete structure, and wherein the control means is connected to the plurality of reference electrodes to receive a plurality of signals from which the control means determines the value Ea,on. 
     
     
       7. The apparatus of claim 6, wherein the control means determines the value Ea,on by determining the mean value of the signals received from the plurality of reference electrodes. 
     
     
       8. The apparatus of claim 6, wherein the control means determines the value Ea,on by determining the root-mean-square of the signals received from the plurality of reference electrodes. 
     
     
       9. The apparatus of claim 1, wherein the control means comprises data processing means. 
     
     
       10. The apparatus of claim 1, further comprising memory means connected to the control means. 
     
     
       11. The apparatus of claim 1, further comprising alarm means connected to the control means, and wherein the control means activates the alarm means when the supplied voltage exceeds a predetermined voltage. 
     
     
       12. The apparatus of claim 1, wherein the anode structure is covered by cement. 
     
     
       13. A cathodic protection system comprising: a metallic reinforcement member embedded in concrete;   an anode net structure overlaying the concrete in which the metallic reinforcement member is embedded;   a reference electrode embedded in the concrete between the metallic reinforcement member and the anodic structure;   power supply means connected to the anode structure by anodic feeding cables and to the metallic reinforcement member for supplying a voltage, whereby the metallic reinforcment member behaves as a cathode;   control means connected to the power supply unit to receive a signal having a value E, the control means also being connected to the reference electrode to receive a signal having a value Ea,on, the control means further being connected to the power supply unit for adjusting the voltage supplied thereby whereby   -E+Ea,on+Em        is greater than a predetermined minimum protection potential, and wherein E is a value indicative of the voltage of the power supply unit; Ea,on is a value indicative of a generally uniform potential between the anode net structure and the reference electrode; and, Em is a value indicative of ohmic drops in the anodic structure and the anodic feeding cables.   
     
     
       14. The apparatus of claim 13, wherein the power supply unit operates at a constant voltage. 
     
     
       15. The apparatus of claim 13, wherein the power supply unit operates at a constant current. 
     
     
       16. The apparatus of claim 13, wherein the predetermined minimum protection potential is -0.90 volts with respect to a Ag/AgCl electrode for pre-stressed concrete. 
     
     
       17. The apparatus of claim 13, wherein the predetermined minimum protection potential is -1.1 volts with respect to a Ag/AgCl electrode for reinforced concrete. 
     
     
       18. The apparatus of claim 13, further having a plurality of reference electrodes embedded in the concrete structure, and wherein the control means is connected to the plurality of reference electrodes to receive a plurality of signals from which the control means determines the value Ea,on. 
     
     
       19. The apparatus of claim 18, wherein the control means determines the value Ea,on by determining the means value of the signals received from the plurality of reference electrodes. 
     
     
       20. The apparatus of claim 18, wherein the control means determines the value Ea,on by determining the root-mean-square of the signals received from the plurality of reference electrodes. 
     
     
       21. The apparatus of claim 13, wherein the control means comprises data processing means. 
     
     
       22. The apparatus of claim 13, further comprising memory means connected to the control means. 
     
     
       23. The apparatus of claim 13, further comprising alarm means connected to the control means, and wherein the control means activates the alarm means when the supplied voltage exceeds a predetermined voltage. 
     
     
       24. The apparatus of claim 13, wherein the anode net structure is covered by cement.